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A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11The LT3042 is designed to make a linear regulator’s output quieter by separating voltage programming from the main feedback path. A precision 100 µA current source feeds the SET pin, while a rail-to-rail buffer follows that programmed voltage at unity gain. The approach helps keep noise, power-supply rejection ratio (PSRR), and transient behavior substantially independent of the selected output voltage.
What makes an LDO quiet?
A low-dropout regulator (LDO) supplies a regulated voltage with little headroom between its input and output. But an LDO can also pass noise from its input or add noise of its own. Two useful measures are output-noise voltage over a stated frequency range and PSRR, which describes how well the regulator suppresses changes on its input. Neither number alone tells the whole story: compare noise over the band relevant to the circuit, and PSRR at the frequencies where input ripple or interference occurs.
The LT3042 uses a 100 µA precision current source and a high-performance rail-to-rail buffer configured as a unity-gain follower. A resistor from SET to ground programs the output voltage. A capacitor from SET to ground filters noise on the reference node, improving output noise and PSRR and helping transient response. The trade-off is longer startup because the capacitor must charge. The architecture’s unity-gain signal path avoids the output-voltage-dependent gain associated with a traditional resistor-divider feedback arrangement, so key performance characteristics are substantially independent of the programmed output voltage, according to Sam Davis’s 2015 Electronic Design article.
What the published LT3042 figures show
Sam Davis’s 2015 Electronic Design article reports the following LT3042 figures. They are published performance figures, not a substitute for checking the conditions and limits in the datasheet for a particular design.
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#1 Best Overall
- 1PCS LT3042 PSRR Ultra Low Noise Linear Voltage Regulator Power Module
- The LT3042 is a high-performance, low-voltage linear regulator that uses ultra-low noise and ultra-high PSRR architecture to power noise-sensitive applications
- The LT3042 is designed as a high precision current reference followed by a high performance voltage buffer that can be easily paralleled to further reduce noise, increase output current, and spread heat on the PCB
- The LT3042 can be powered up to 200mA with a typical dropout voltage of 350mV. The nominal quiescent current is 2mA and is reduced to <<1μA in shutdown mode
- The LT3042's wide output voltage range (0V to 15V) and ability to maintain unity-gain operation provide virtually constant output noise, PSRR, bandwidth, and load regulation regardless of the programmed output voltage.
| Measure | Published figure | Source and qualification |
|---|---|---|
| Integrated output noise | 0.8 µV RMS, 10 Hz to 100 kHz | Electronic Design, Sam Davis, 2015 |
| Spot noise | 2 nV/√Hz at 10 kHz | Electronic Design, Sam Davis, 2015 |
| Low-frequency PSRR | More than 90 dB to 10 kHz | Electronic Design, Sam Davis, 2015 |
| High-frequency PSRR | More than 75 dB to 3 MHz | Electronic Design, Sam Davis, 2015 |
| Output current and dropout | 200 mA output at typically 350 mV dropout | Electronic Design, Sam Davis, 2015 |
For context, TI’s 2015 TIDU996 application report reports LP5907 output noise of 6.5 µV RMS at 1 mA and 10 µV RMS at 250 mA, both over 10 Hz to 100 kHz. It reports PSRR of 90 dB at 100 Hz, 82 dB at 1 kHz, and 65 dB at 10 kHz. Those are measurements for that TI design and regulator under its documented conditions; they should not be treated as a direct apples-to-apples LT3042 comparison without matching test setup and conditions.
What capacitor and layout does the LT3042 need?
The LT3042 requires an output capacitor for stability. The 2015 Electronic Design article specifies a minimum 4.7 µF output capacitor with ESR below 50 mΩ and ESL below 2 nH. The article also recommends Kelvin connections for OUTS and for the ground return of the SET capacitor. These details matter because parasitic resistance and inductance can undermine the noise and stability performance the circuit is meant to achieve.
Rank #2
- Ultra Low Noise Performance: Features the high-performance LT3042 regulator chip, providing ultra-low noise and high power supply accuracy—ideal for RF, audio, and sensitive analog circuits.
- Multiple Output Voltages: Supports selectable output voltages of 3.3V, 5V, and 12V, meeting a variety of project needs for different devices and modules.
- Single Power Input: Simplifies power management with a single input, making it easy to integrate into existing setups or DIY electronics.
- Stable & Reliable: Delivers excellent voltage stability and load regulation, ensuring consistent power delivery for high-fidelity and high-frequency applications.
- Versatile Application: Perfect for powering RF modules, audio amplifiers, DACs, microcontrollers, laboratory instruments, and other precision electronics projects.
- Output capacitor: use at least 4.7 µF and observe the stated ESR and ESL limits.
- SET capacitor: connect from SET to ground to filter reference noise; allow for the resulting longer startup.
- Kelvin routing: use Kelvin connections for OUTS and the SET-capacitor ground as recommended.
- More capacitance: larger capacitance mainly reduces peak output deviation during load transients, while reducing bandwidth.
The same article gives shutdown current below 1 µA and nominal operating quiescent current of 2 mA. Include the operating current and dropout in power and thermal calculations rather than evaluating noise in isolation.
How to choose a low-noise LDO for an audio or precision rail
Start with the rail polarity, voltage range, maximum load, and the frequencies of concern. Then compare the candidate parts using the same kinds of measurements and design constraints rather than selecting solely by the lowest headline noise number.
Rank #3
- Ultra Low Noise Performance: Features the high-performance LT3042 regulator chip, providing ultra-low noise and high power supply accuracy—ideal for RF, audio, and sensitive analog circuits.
- Multiple Output Voltages: Supports selectable output voltages of 3.3V, 5V, and 12V, meeting a variety of project needs for different devices and modules.
- Single Power Input: Simplifies power management with a single input, making it easy to integrate into existing setups or DIY electronics.
- Stable & Reliable: Delivers excellent voltage stability and load regulation, ensuring consistent power delivery for high-fidelity and high-frequency applications.
- Versatile Application: Perfect for powering RF modules, audio amplifiers, DACs, microcontrollers, laboratory instruments, and other precision electronics projects.
- Noise: compare integrated noise over the frequency band that affects the application, and spot noise where a narrow-band sensitivity matters.
- PSRR: examine rejection across the frequency band of the upstream converter’s ripple and other interference; one low-frequency PSRR figure is not enough.
- Current and dropout: check the required output current and the input-to-output headroom at that load.
- Voltage and polarity: verify input and output ranges and whether the rail is positive or negative.
- Stability and layout: check capacitor requirements, ESR/ESL limits, and pin-routing guidance in the exact datasheet revision.
- Thermal headroom and package: calculate regulator dissipation for the actual input, output, and load, then confirm the package can handle it in the intended board conditions.
- Lifecycle and availability: confirm current status and supply from the manufacturer and authorized distributors before committing a design.
Related options and an audio reference design
LT3045 for a higher-current positive rail
The LT3045 is a related higher-current option. Analog Devices describes it as using LTC’s ultralow-noise, ultrahigh-PSRR architecture for noise-sensitive applications. Its CN-0511 demo design documents a 500 mA design operating from 3.8 V to 20 V. Treat those as demo-design operating details, not as a blanket statement about every LT3045 circuit.
ADP7182 for negative rails
The ADP7182 is a negative LDO covering −2.7 V to −28 V and up to −200 mA. Analog Devices’ current product page reports 18 µV RMS output noise and 66 dB PSRR at 10 kHz at a −3 V output. Those figures are tied to the stated output condition and should be evaluated against the noise and rejection needs of the actual negative rail.
Rank #4
- Voltage Regulator for Husqvarna: 966042901 966612301 RZ3016 LTA18538 YTA22V46 YTH18542 YTH24V54 Z246 Z246I Tractor
- Package Includes: 1- Voltage Regulator
TI TIDA-00571 for hi-fi audio
TI’s TIDA-00571 is a low-noise, high-PSRR LDO reference design for hi-fi audio. TI provides design files, assembly drawings, and a bill of materials. Its application report presents LP5907 measurements and frames the design as a quiet alternative to a standard buck converter for audio power. A reference design can help with implementation, but its measured results still depend on its documented components, setup, and conditions.
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